Precision N rates for dryland farming? Financial analysis of precision variable-rate nitrogen (VRN) in Northeast Victoria

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Abstract

Presented at conference on science, technology, engineering and economics for Digital Agriculture (steeDA), University of Sydney, 3-5 Dec 2019

Physical and financial data from cooperating farmers near Corowa were analysed, including detailed geo-referenced header yield records from harvests between 2000 to 2017.
Historical long-term whole-farm average yields each year for two farms were used to calculate best-fit yield response curves against growing season rainfalls (GSR). R2 values for quadratic curves of wheat and canola were 76% and 84%, respectively, with both crops showing increasing yield depression at high GSR, caused by localised waterlogging.
Within-paddock variability with respect to GSR is illustrated in the cases of three paddocks for which yields of geo-referenced 90 x 90m grid areas were available over five or six years, including dry and wet seasons. Grid area responses to GSR differ, some yielding better than average in dry years but worse in wet, and others performing worse than average in the dry but best in the wet. Consequently, there was less than 5% chance that the first-year yield quartile for any individual grid area would be repeated over the next four years. Real-time NVDI appeared to be a more accurate indicator of future yield and profitability than either historical yield or EM38 measurements.
Replicated N-rate trials located in low and high EM38 zones on two farms showed no consistent yield response. Under these conditions the long-term, risk adjusted, break-even cost of implementing VRN would be met by less than 1% increase in yield, or 70% decrease in the amount of N fertiliser applied.
Original languageEnglish
Number of pages31
Publication statusPublished - 05 Dec 2019
EventsteeDA: science, technology, engineering, and economics for Digital
Agriculture Conference
- The University of Sydney, Camperdown, Australia
Duration: 03 Dec 201905 Dec 2019
https://sydney.edu.au/content/dam/corporate/documents/sydney-institute-of-agriculture/outreach-engagement/steeda-conference-draft.pdf

Conference

ConferencesteeDA: science, technology, engineering, and economics for Digital
Agriculture Conference
Abbreviated titlescience technology engineering and economics for Digital Agriculture
CountryAustralia
CityCamperdown
Period03/12/1905/12/19
Internet address

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  • Cite this

    Nordblom, T., Godfrey, S., Hutchings, T., & Schefe, C. (2019). Precision N rates for dryland farming? Financial analysis of precision variable-rate nitrogen (VRN) in Northeast Victoria. Paper presented at steeDA: science, technology, engineering, and economics for Digital
    Agriculture Conference, Camperdown, Australia.